British supermarkets have been placed on high alert after shops across Europe were hit by cyber hackers who seized control of their fridges and freezers.

The National Cyber Security Centre – a wing of intelligence agency GCHQ – has warned retailers to be aware of the threat following the attacks, which have caused widespread damage.

Dozens of supermarkets in Belgium, Sweden, Ireland, Luxembourg and Estonia have been targeted – just weeks after hackers turned up the temperatures of cooling units in hundreds of French grocery stores.

The latest attack involved a number of fridges manufactured by Belgian firm Sabcobel. The company said units' evaporators were switched to defrost mode, causing temperatures to spike from -27C to 50C in some cases.

It is similar to the method used in last month's attack on French supermarkets, which led to millions of euros' worth of food being thrown away and caused a number of fires.

The French hacks affected fridges supplied by Danfoss, which also works with British supermarkets including Tesco and Sainsbury's.

Around 40 Delhaize and Colruyt supermarkets in Belgium and Luxembourg were hit, along with 15 Carrefour stores.

Ikea said its retail refrigeration control systems at one store in Belgium had also been affected and said it 'cannot rule out' whether additional locations have been affected.

Swedish grocers ICA and Coop reported similar temperature spikes.

Stephan Moelans, CEO of Sabcobel, which operates Delhaize's systems, described the incident as a cyber-attack.